Forgive a dumb question, But What is stop down metering?

I bought a very used set of extension rings, and a very used Nikkor
85mm f/2.8 PC lens, and a "beater" 35mm PC lens from a local camera
store at a fair price, I think, $ 550.00. I bought it to use with my
F3, But I'm told that I must use "Stop Down" metering. I called and
spoke to a tech at Nikon, who was less than helpful. In fact he
didn't even know you could use the extension tubes with the 85mm.
Sooooo, I thought why not ask you.

Well, forgive my dumbness, being relatively new to this, but what
is "stop down metering"? We never coverd this in college, or I
might have had a hangover when we did ;)

Thanks allot for your help

Abbie

Responses

stop down metering just means that you have to meter at the aperture you are shooting at. unlike most AI lenses, where you set the aperture to where you want and it stays at full aperture until right before you take the picture.

that has a little on how to perform stop down metering. if you have the camera manual, that would also be another place to check. im not familiar with the lenses or with stop down metering, other than the definition.

With the 35mm PC lens you don't have to do a thing. When you turn the aperture ring to the desired f/stop the meter will automatically account for the reduced light transmission. Also, the viewfinder will darken.

With non-AI, auto-diaphragm lenses on the F3 you'll need to depress the silver button on the front right of the body - this closes down the aperture and allows accurate metering.

Stop-down metering is unnecessary with any lens when used at full aperture - the meter simply reads the full aperture setting.

BTW, with non-AI, auto-diaphragm lenses you'll need to flip the meter indexing tab on the F3 out of the way to prevent damage. It's a little silver tab at around the 1 o'clock position, facing the camera mount. Press the tiny button to the right of the tab to release the hinged tab.

Most Nikkor lenses are Auto-Aperture lenses. That is they stop down just an instant before the photo is taken automatically. Some lenses are Preset. These lens will have two aperture rings. One you preset to the aperture ratio you want to use and the other your rotate with a finger just before taking the picture to accutally stop down the lens. This second ring will stop the lens down to the "preset" or chosen aperture.

Auto-Aperture lenses require a coupling to tell the camera how many stops from maximum aperture the lens will close for the shot. The cameras meter can then calculate the proper exposure. This can be an AI (auto-indexing) lens with a ridge on the aperture ring or the old "rabbit ears." If an extension tube is used that breaks the indexing mechanism or if the lens is mismatched such as an early non-AI lens is used on the F3 then the lever that senses the aperture on the F3 needs to be flipped up. The lens can then be mounted and the important part follows...

For Auto Aperture lens or lenses used with non-AI extension tubes you press the Depth of Field Preview Button and take a Stop-Down Reading with the lens stopped down to the chosen aperture. The DOF Preview button need not be held down once the reading is taken.

With the Preset lens you rotate the second aperture ring to stop down the lens to the preset aperture and then with the lens stopped down take a reading. Both rings can be rotated together for convenience.

Some lenses or optical devices dont have an aperture control and they are always stopped down so you just take a reading.

The important concept is if no linkage tells the camera how many stops the lens WILL be stopped down then the lens MUST be stopped down to the taking aperture while a meter reading is taken. Since the lens must be "stopped down" manually the technique is called Stop-Down Metering. Once youve done it a few times it will be easy and make perfect sense.